This project seeks to understand the molecular basis of the interactions of P. gingivalis, a major periodontal pathogen, with the extracellular matrix component, fibronectin. This interaction takes place in an iron- poor environment, but is destroyed in an iron-rich environment, in which protease activity is elevated. Bifunctional crosslinking agents will be used to determine the surface receptor on P. gingivalis. In a second set of experiments, recombinant domains of fibronectin produced in collaboration with Dr. Paul Johnson (Project 2 and Core 9001) will be used in competition experiments to establish which domain(s) of fibronectin interact with the surface of P. gingivalis.